Just to toss in my $00.02.
I also have been employeed in the aquarium idustry at the retail end so I can vouch for the claim that too many in the pet hobbies are irresponsible. The exotic invasives in southern Florida are a case in point. The number of exotic fish, reptiles and birds found in Florida is staggering and growing all the time. I'm refering to reproducing populations, not just your average stray. Many, if not most are released by pet owners. The only reason it is not more widespread in the US is climate.
That mitigating factor becomes moot when temporate species become popular pets. Many states are now passing or trying to pass laws banning specific animals deemed able to reproduce in a temporate climate. Personally, I'm not a big fan of more regulations, but what other option is there? Ironically, many states have F&G regs which prohibit collection of non-game native species thereby preventing concerned hobbiests from keeping only those animals native to their state, regardless of how abundant and secure a given population may be. Kind of a Catch 22.
So what's the answer? Don't know. On one hand, better education of pet hobbiests might prevent some problems. Unfortunately, mis-information or total lack of information is the norm. One need only visit the fish department of any of the supermarket chain type pet stores and ask the teenage clerk a few questions. No help there!
On the other hand, promoting the collecting and culture of secure, abundant native species would at least slow down the importation of exotics. Unfortunately, that is a concept which is generally viewed in a dim light by most state DMR - F&G types. To me, that's the ultimate irony. Think about it - what group of people in the history of this country have been responsible for the introduction of the most exotic species? F&G of course! I defy anyone to find a body of fresh water anywhere in the northeast which does not contain an introduced species! Brown trout, rainbow trout, largemouth bass, bluegill, northern pike etc etc. Our tax dollars and license fees have paid for those exotic introductions and I rarely hear anyone complain!
Oh, and for what it's worth, I've delt with various species of snakehead in the past. One thing is for sure - they are almost industructable! They certainly CAN "breath" air in the traditional fish way, via their gills. The fact that they can also take atmospheric air from the surface means they can live in degraded, oxygen poor, polluted waters which would kill most other fish. Also, I have known them to be kept for years in unheated room temp tanks in New England so a low end temp of 70 F is pretty optimistic. Personally, I'd place it at least 10 degrees lower, if not more.